Quite close, unsafe package and method declaration come from Oberon-2 (thanks Robert Griesemer), everything else is somehow inspired from Limbo.

https://www.vitanuova.com/inferno/limbo.html

https://www.vitanuova.com/inferno/docs.html

If I remember correctly, they have similar concurrency models. They were both written the same author as well, Rob Pike.

Edit: fixed a typo